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• What is the purpose of CHAPTER END in video metadata ?

  20 décembre 2022, par Cypc

  I am learning how to use ffmpeg to add chapters to fairly long recordings as a mean of remembering key timestamps.
After a successful test I got my chapters showing in VLC as little marks on the time bar and in chapter menu, but those marks correspond to START time obviously.

  


  So what is the purpose of END time ? It does not seem to do anything in VLC, is it important to have a chapter starting at the start of the video and one ending at the end of the video ? Is it important to have each chapter end when the next one starts ?

  


  [CHAPTER]
TIMEBASE=1/1
START=1
END=600
title=Chapter


  


• Is it possible to adjust position of gdigrab recording region during recording ?

  30 novembre 2020, par adelima

  I'm using ffmpeg for recording video from defined desktop region by starting ffmpeg.exe as process with arguments like so :

  


      public static void StartRecording(Video v) {
        string outPath = Path.Combine(Application.StartupPath, "rec", $"{v.FileName}.mkv");
        v.FFMPEG = new Process {
            StartInfo = new ProcessStartInfo() {
                Arguments = $"-hide_banner -y -thread_queue_size 512 -f gdigrab -offset_x {v.Bounds.X} -offset_y {v.Bounds.Y} -video_size {v.Bounds.Width}x{v.Bounds.Height} -show_region 0 -i desktop -vf \"scale=trunc(iw/2)*2:trunc(ih/2)*2\" -c:v libx264 -preset ultrafast -crf 18 -pix_fmt yuv420p \"{outPath}\"",
                WindowStyle = ProcessWindowStyle.Hidden,
                CreateNoWindow = true,
                UseShellExecute = false,
                FileName = Path.Combine(Application.StartupPath, "bin", "ffmpeg.exe"),
                RedirectStandardOutput = true,
                RedirectStandardInput = true,
                RedirectStandardError = true,
            }
        };
        v.FFMPEG.Start();

        new Thread(() => {
            using(StreamReader sr = v.FFMPEG.StandardError) {
                while(!sr.EndOfStream) {
                    Debug.WriteLine(sr.ReadLine());
                }
            }
        }).Start();
    }

    public static void StopRecording(Video v) {
        using(StreamWriter sw = v.FFMPEG.StandardInput) {
            sw.WriteLine("q\n");
        }
        v.FFMPEG.WaitForExit();
        v.FFMPEG.Dispose();
    }


  


  Is it possible to make changes to the -offset_x and -offset_y arguments during recording ? I'm drawing the recording region bounds with directx and want to add a titlebar to it which can be dragged to move the recording region, but I'm not sure how I would let ffmpeg know that I want these offsets changed or whether it's even possible.

  


• avcodec/aaccoder : Add minimal bias in search_for_ms()

  31 mai 2021, par Michael Niedermayer

  avcodec/aaccoder : Add minimal bias in search_for_ms()
  Fixes : floating point division by 0
  
  Fixes : Ticket8218
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavcodec/aaccoder.c